Our long term goal is to understand the molecular mechanisms of regulation of eukaryotic mRNA gene transcription. A comprehensive knowledge of transcriptional regulatory mechanisms is absolutely essential if we are to understand normal and pathological biological processes and conditions. Our studies utilize Bakers Yeast, Saccharomyces cerevisiae, as a model system for elucidating the detailed role that factor TFIID plays in the complicated process of mRNA gene transcription by RNA polymerase II. These studies are an outgrowth of our recent work on TBP the TATA-box Binding Protein, which we currently know is a subunit of at least two distinct RNA Polymerase II-specific multiprotein complexes: (1) it comprises the DNA- binding subunit of TFIID and (2) a complex containing at least one additional protein termed TAF170, TBP Associated Factor of Mr about 170,000. Work from a large number of different investigators has demonstrated that the multisubunit, TBP-containing TFIID complex is intimately involved in the regulatory events which actually control mRNA gene transcription. Hence, understanding the composition and function of TFIID/TBP and other TBP-containing complexes is key to knowing how gene transcription is controlled. The approach which we will be used i our experiments will be multi-faceted combining biochemical and genetic analyses focusing upon yeast TBP and the genes encoding the multiple yeast TAFs which we have recently cloned. We will examine the interplay of these factors with TBP, each other, promoter DNA, and RNA polymerase II. Successful completion of these experiments will greatly increase our understanding of the key process of RNA polymerase II transcription.